Effect of annealing on the formation of p-type conductivity in nano-Zn0.92Mn0.08O:N films.

: P-type conductive Mn-N co-doped ZnO films were prepared by annealing N(+)-implanted Zn0.92Mn0.08O films in a N2 ambient. Effect of the annealing on the structural, surface morphological, electrical and local chemical states of the films were investigated by X-ray diffraction (XRD), high-resolution field-emission scanning electron microscopy (FE-SEM), Hall-effect and X-ray photoelectron spectroscopy (XPS) measurements, respectively. The results indicate that all the samples were single phase and well oriented along the c-axis. The as-implanted samples were n-type semiconductors, while after thermal annealing at 650 degrees C ranging from 10 to 30 minutes, they were converted to p-type conductivity with the hole concentration of 10(16)-10(17) cm(-3). But with further increasing the annealing time or the temperature, it was observed that the p-type conductivity decreased and ultimately reverted to n-type conductivity again. The change of conductive type may be ascribed to the local chemical states evolution of nitrogen in the process of thermal annealing.